Field
The present disclosure relates to a head and an atomic force microscope having the same, and more particularly, to a head having improved usability by limiting a movement range of a laser spot and an atomic force microscope having the same.
Description of the Related Art
A scanning probe microscope (SPM) represents a microscope that measures a surface characteristic of a sample and shows the measured surface characteristic as a 3D image while making a minute probe manufactured through an MEMS process scan the surface of the sample. The scanning probe microscope may be subdivided into an atomic force microscope (AFM), a scanning tunneling microscope (STM), and the like according to a measurement method.
FIG. 1 is a schematic perspective view of an atomic force microscope in which an XY scanner and a Z scanner in the related art and FIG. 2 is a schematic conceptual diagram of a head used in the atomic force microscope having a structure of FIG. 1.
Referring to FIG. 1, the atomic force microscope 10 is configured to include a cantilever 2 following the surface of a measurement target 1 in a contact or non-contact state, an XY scanner 11 scanning the measurement object in X and Y directions on an XY plane, a Z scanner 21 connected with the cantilever 2 to move the cantilever 2 in a Z direction with a comparatively small displacement, a Z stage 12 moving the cantilever 2 and the Z scanner 21 in the Z direction with a relatively large displacement, and a fixing frame 13 fixing the XY scanner 11 and the Z scanner 12.
The atomic force microscope 10 acquires an image such as topography, or the like by scanning the surface of the measurement object 1 with the cantilever 2. Relative movement of the surface of the measurement object 1 and the cantilever 2 may be performed by the XY scanner 11 and the cantilever 2 may be vertically moved by the Z scanner 21 so as to follow the surface of the measurement object 1.
Meanwhile, the cantilever 2 and the Z scanner 21 are connected by a probe arm 22 and a head 20 including the probe arm 22 and the Z scanner 21 is not explicitly illustrated in FIG. 1.
Referring to FIG. 2, the head 20 is configured to serve to measure a motion (for example, a bending degree) of the cantilever 2 by using a laser system and provide the measurement motion to a controller (not illustrated).
The head 20 has a laser beam generating unit 23 irradiating a laser beam and the laser beam generating unit 23 irradiates the laser beam to a mirror 24 fixed to an intermediate body 28. The laser beam is directly reflected by the mirror 24 and thereafter, passes through a hole formed in the intermediate body 28 to be reflected on the top surface of the cantilever 2 again. The reflected laser beam is again reflected by a steering mirror 25 to focus on a beam detecting device 26. Herein, as the beam detecting device 26, a position sensitive photo detector (PSPD) is primary used and the laser spot is positioned at the center of the PSPD, and as a result, measurement preparation is completed. The Z scanner 21 is controlled based on a signal detected by the beam detecting device 26. The beam detecting device 26 may be installed to be fixed to a housing 30 of the head 29 and a detailed layout relationship is omitted for easy description.
In order to position the laser spot at the center of the beam detecting device 26, first, focusing the laser spot on the top surface of the cantilever 2 needs to be preceded. A user manually adjusts the laser spot to be positioned on the top surface of the cantilever 2 by operating control knobs 27A and 27B as a spot moving means while visually verifying whether the laser spot is positioned on the top surface of the cantilever 2 by using a vision system (not illustrated) which may view the top of the cantilever 2. Control knobs 27A and 27B changes a slope of the intermediate body 28 supporting the mirror 24 to change a path of the laser beam. For example, the control knob 27A may cause movement of the laser spot in a width direction of the cantilever 2 and the control knob 27B may cause movement of the laser spot in a longitudinal direction of the cantilever 2.
A location area (hereinafter, referred to as ‘spot area’) of the laser spot which is adjustable by the control knobs 27A and 27B is widely designed by reflecting an assembly tolerance, and the like in order to accommodate cantilevers 2 having various sizes.
However, the widely designed spot area brings about inconvenience for use. The user focuses the laser spot on the top surface of the cantilever 2 by adjusting the control knobs 27A and 27B again at the time of changing the cantilever 2 and since the spot area is large, the laser spot is frequently lost in the vision system. Users which are not familiar to the device unnecessarily consumes a lot of time to position the laser spot on the top surface of the cantilever 2 to feel inconvenience for use.